As is well known, the evaporator of an automobile air conditioning system is normally combined with the usual components which provide heated and ventilated air to the interior of the automobile. The unit incorporating such components is made as a module type assembly which is attachable to the fire wall of the vehicle and includes a housing supporting the heater core, evaporator, and the blower within suitable duct work provided with valves for directing air flow through the evaporator and/or the heater core and into the vehicle interior. Thus, by operation of a heater/air conditioning control unit located on the instrument panel, the driver can selectively provide heated, cooled, or outside air into the passenger compartment of the automobile.
Inasmuch as the heater core and the evaporator core have fluid flowing therethrough, a pair of pipes are connected to each for allowing the fluid to enter and leave the core. In this regard, it has been found that in certain U-flow evaporator designs difficulties can be encountered in providing sufficient space for routing the piping of both of the cores within and without the support casing. This is particularly true when the evaporator has the refrigerant inlet located long one side of the evaporator core and the outlet located at the front end of the core. In this form of the evaporator, long pipes are required for connection with the other components of the system. One form of evaporator design which requires the inlet and outlet ports be so located is the so-called six pass design wherein the refrigerant flows into three blocks of U-flow tubes for reversing the direction of flow and passes in front of the blower forced air six times. In certain vehicles, it would be advantageous to locate the inlet and outlet ports of the six pass evaporator internal to the tube sections for packaging reasons, but presently it is not possible to do so.